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Topic: More Sigma Primes Coming? [CR1] (Read 19514 times)

Sigma adding to the prime lineup
With the success and quality of the Sigma 50 f/1.4 and 85 f/1.4, Iâ€™m told theyâ€™ll be adding more fast primes to the lineup over the next 18 months.

Lenses on the horizon may include a 24 Ã‚ f/1.4, 35 f/1.4 and 135 f/2.

Sigma will also continue to update lenses by adding OS to them. The 300 f/2.8 may be the first to get OS along with the 500 f/4.5. With the pricing of the new Canon lenses in these focal ranges, I wouldnâ€™t be shocked to see Sigma do something 20% cheaper.

Flake

Sigma's primes are not without their problems though. The 50mm in particular suffers from focus shift when stopping down, the issue is worse on Canon cameras because the autofocus has the more sensitive f/2.8 centre point as opposed to other makes on f/5.6. When you focus with the lens wide open at say F/2.8 the focus is at one point, when the shutter is released the aperture snaps down, and the point of focus moves, in many cases ruining the shot.

This has been the issue many users have reported since the lens was released. On the other hand Canon's own f/1.4 although optically good suffers reliability issues, and should really be replaced. The 80mm f/1.8 is a very good lens, cheap too, it's difficult to see why anyone would pay a lot more money for a one stop advantage (especially if it suffers focus shift).

Sigma's primes are not without their problems though. The 50mm in particular suffers from focus shift when stopping down, the issue is worse on Canon cameras because the autofocus has the more sensitive f/2.8 centre point as opposed to other makes on f/5.6. When you focus with the lens wide open at say F/2.8 the focus is at one point, when the shutter is released the aperture snaps down, and the point of focus moves, in many cases ruining the shot.

This has been the issue many users have reported since the lens was released. On the other hand Canon's own f/1.4 although optically good suffers reliability issues, and should really be replaced. The 80mm f/1.8 is a very good lens, cheap too, it's difficult to see why anyone would pay a lot more money for a one stop advantage (especially if it suffers focus shift).

Could you explain what causes the focus shift? Why would the point of focus move when the iris closes to the setpoint (unless that causes other things to move in the front-to-rear direction)?

I also really like Canon's 85mm f/1.8, and my copy of the 50mm f/1.4 has been fine so far, so again, I'm happy with that. Having bought, and immediately returned, a bad copy of the Sigma 30mm f/1.4 (it was terrible), I'm wary of Sigma lenses. OTOH right now it's a non-issue, cos I'm still paying off the 24-105 f/4 L! So nothing at all is gonna get bought for a couple of months!

Really this would rock the boat a bit, with canon currently charging over a Â£1000 for their version of this 24mm lens and the 50mm f1.4's being much closer in price at about Â£300s- maybe an affordable amatuer level.

I'm guessing canon prices would drop a bit or they would nedd to make a f1.2 version to stay ahead.

But while I heard a lot about inconsistent focus of the Siggy Fifty, I haven't heard about residual spherical aberations/focus shift in this one. However, the Canon 50 1.2 exhibits this problem quite clearly.Check, e.g., this out for a serious discussion of the issuehttp://photography-on-the.net/forum/showthread.php?t=371097(or simply google for "50L focus shift"...)

and this for a more tongue-in-check view on the "50L focus issues" topic

But while I heard a lot about inconsistent focus of the Siggy Fifty, I haven't heard about residual spherical aberations/focus shift in this one. However, the Canon 50 1.2 exhibits this problem quite clearly.Check, e.g., this out for a serious discussion of the issuehttp://photography-on-the.net/forum/showthread.php?t=371097(or simply google for "50L focus shift"...)

and this for a more tongue-in-check view on the "50L focus issues" topic

Sigma's primes are not without their problems though. The 50mm in particular suffers from focus shift when stopping down, the issue is worse on Canon cameras because the autofocus has the more sensitive f/2.8 centre point as opposed to other makes on f/5.6. When you focus with the lens wide open at say F/2.8 the focus is at one point, when the shutter is released the aperture snaps down, and the point of focus moves, in many cases ruining the shot.

This has been the issue many users have reported since the lens was released. On the other hand Canon's own f/1.4 although optically good suffers reliability issues, and should really be replaced. The 80mm f/1.8 is a very good lens, cheap too, it's difficult to see why anyone would pay a lot more money for a one stop advantage (especially if it suffers focus shift).

Could you explain what causes the focus shift? Why would the point of focus move when the iris closes to the setpoint (unless that causes other things to move in the front-to-rear direction)?

I also really like Canon's 85mm f/1.8, and my copy of the 50mm f/1.4 has been fine so far, so again, I'm happy with that. Having bought, and immediately returned, a bad copy of the Sigma 30mm f/1.4 (it was terrible), I'm wary of Sigma lenses. OTOH right now it's a non-issue, cos I'm still paying off the 24-105 f/4 L! So nothing at all is gonna get bought for a couple of months!

Thanks.

Martin

Here's review of the sigma 50 1.4 at photozone (http://www.photozone.de/canon-eos/521-sigma50f1450d?start=1 ). The graphic near the bottom is pretty self-explanatory. The effect is due to residual aberrations, and it is bad lens design. Focus moves back about 2 cm when stopping down to f4. That's pretty bad.

You can get good focus using live-view, and by f8 the DOF is so big that your focus point will be covered and you will not see this effect. Of course there is no effect at f1.4, but it will be quite annoying between f2 - f5.6, and this is the only reason that I bypassed this lens: f1.4 is soft, focus is unreliable for f2.0 - f5.6, and I have plenty of other options for good shots at f5.6 and above.